MBC not working, nothing changes no matter how its hooked up.

[cyclist112]

I installed an mbc, following directions i found on here, and it does nothing. My mbc is one of the cheap ones from ebay, which i am away could be one of the issues. what confuses me is that when i take out the MBC and run the hose directly from the vacuum to the wastegate, it still does nothing. To my knowledge(which im new with turbos so its not extensive), that should make the turbo max out its boost, yet nothing changes. Could my wastegate be bad or some part be bad that is preventing my car from going over stock boost?

 

[LiquidX]

Hooking up the vacuum line from your pressure source to the wastegate will cause you to only run a max psi of what the spring is capable of. Nothing more, nothing less unless there is a leak or you have poor wastegate flow.

How do you have your lines routed, what are they hooked up to? What kind of MBC is it? Is your wastegate operating properly (actuator arm sticking on anything or flapper stuck open?)?

 

[69_luv]

Where is the source coming from? Not the factory bcs or intake tube right? Does your turbo have a boost source? If your turbo doesn't have a boost source try tee'ing off the bov (only if your turbo or j-pipe don't have a boost/vac nipple). Try a vac line straight to the wastegate from the T off the vac line going to the BOV and you should only see the max boost that your wg allows (most of the 16g's that I know of are around 11psi). If that works then try to install the mbc off that same vac line. If it is not working do a full BLT, and possibly see if you can bum another mbc for testing. There isn't much to a mbc, so either you have it hooked up wrong, you have a kink, leaks, or have the knob turned the wrong way...
Pictures always help if you could snap one and post.

 

[JusMX141]

To my knowledge(which im new with turbos so its not extensive), that should make the turbo max out its boost, yet nothing changes.

Wrong. Doing this will generate the least amount of boost possible.

Could my wastegate be bad or some part be bad that is preventing my car from going over stock boost?

If I had to guess, I would blame a shitty manual boost controller.


Try winding the screw in as far as it goes then back it out a turn or two and see what happens....maybe the Chinamen that built it never installed a spring.

 

[cyclist112]

Its ran from from the BOV tee to the mbc too the wastegate. I just played with it a bit and did get it to hit a lower boost when i directly ran the hoes from the BOV Tee to the Wastegate. With it direct ran it appears to be hitting about 8psi, when i had it hooked up to the mbc it was about 11psi with the knob turned all the way out.
In terms of the mbc spring, I have seen people comment about that being an issue and i dont understand how it makes a difference from a mechanical perspective. The way I view it, when its screwed it in lets less air travel through, and when its out it lets more, i cant grasp what it is that the spring does in the equation to make a difference?
As for the wastegate, im not sure how to check if it is working properly or not. I come from working on small black fords with no type of boost so this is all new to me. I am just trying to do a couple simple mods to get a bit more power, nothing extreme, just want a few tenths to drop off the e.t. so i can hang with my buddy.

 

[19Eclipse90]

Run it from the wastegate to the nipple with the screw (your pressure source) in the hose you have pictured. Do NOT "T" into the BOV line.

When you are satisfied it is running or reading how it should, set it up like this (depending on your MBC style): http://www.dsmtuners.com/forums/newbie-forum/365594-help-manual-boost-controller.html#post152154778. There's also this: http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/237982-best-way-install-mbc.html.

 

[cyclist112]

I looked at those links before, and I havent found a nipple on the turbo as it shows in those picture. admittedly I havent dug around too much since i dont have a garage anymore, but i have felt all around and havent found anything like what is shown in the pictures.
In messing with different hookups I did directly hook the hose up from the wastegate to what i believe is called the j-pipe(still trying to learn turbo terms), and managed to get what shows up as about 12-13psi, and then it kind of cuts out once the rpm's and boost is up to high. Am i just running out of fuel to supply the extra amount of air? It may not sound like it because i am confused and still new on turbos, but I am actually somewhat mechanically inclined, so if anyone actually wanted to describe why things are happening, as opposed to just what to do to fix them, i would probably understand much better.
Thanks for the help so far

 

[LiquidX]

If you don't have a nipple on your compressor cover, drill, tap, and install a nipple onto the J-pipe. As stated, NEVER tap into the BOV line.

Filling out your profile will help out a lot.

You are most likely hitting fuel cut as the stock system with the 14b (assuming you have a manual) shouldn't be ran more than 15 psi. If you have larger than a 14b, then your boost will need to go lower due to an increased CFM flow.

 

[Redwan]

i was wonder if anyone here had issues with turbo xs boost control? i've got one hooked up in my 2g dsm and no matter what i do to turn the boost down or up the boost is always at 9lbs, i have it hooked up from the source from jpipe to mbc and mbc to wastegate, same as the pic above, worked fine before, but now its just at 9lbs, wont change at all. any help is appreciated thanks.

 

[cyclist112]

I did some research to understand more how boost controllers and wastegates work, and i think my mbc that i have is labeled backwards, which leads me to a couple questions. first, it shows that if i screw it to the right the boost will increase, but it is reverse threads. From what i understand if you allow more vacuum then the wastegate will open earlier meaning less boost?
After I hooked up the mbc as shown, i have messed with it for a couple days to and from work, and no matter where it is placed it wont go above roughly 10lbsi. when it is adjusted so that less air can flow, it might peak just a bit quicker, but the total boost will not raise.

What could be causing the prevention of the boost from going above 10lbs? The only things I could think of was a wastegate that is stuck open, lack of fuel(which i would assume the stock fuel system could handle more than 10lbs of boost?), or vacuum leak somehow?
I am kind of lost on this, if anyone could help it would be great...

 

[19Eclipse90]

You have a "bleeder" type controller, not the ball and spring, which is why you aren't able to control the boost with what you have. Look at this post again and scroll down to "bleeder" type. You should be able to use any sort of "T" to get it set up correctly.

 

[cyclist112]

Okay, ill try that tonight. Is there anyone that could explain to me how the T works/makes a difference? Im confused on the mechanics of why it makes a difference. Or if someone has a link that explains it that would be great too. Thanks for all the input!

 

[BradM]

My guess is its a crappy ebay mbc. I would try going for a better one. Good luck!

 

[19Eclipse90]

Okay, ill try that tonight. Is there anyone that could explain to me how the T works/makes a difference? Im confused on the mechanics of why it makes a difference. Or if someone has a link that explains it that would be great too. Thanks for all the input!

Google is great, really!

Frequently Asked Questions
Info & FAQ

 

[cyclist112]

okay, believe or not I do know how to, and always do search google to find as much as I can. that being said, the links you posted, still dont actually explain anything different than what I have found, and still doesnt make any sense to me. Why does the T actually make a difference? from looking at those links, it would make since to me that even without the tee, when I have the boost controller all the way in(therefore not letting any air through) it would prevent the wastegate from opening and create maximum boost possible, is this not correct? I do understand how the ball and spring would be more stable and better than a bleeder, but i dont understand why a bleeder, or for that matter anything that obstructs the airflow to the wastegate, wouldnt make max boost...

 

[blue6gen]

Yeah be carefull with that mbc. I have one and it will stop at the set boost settings most of the time but during hard full throtle pullls i have had spikes of almost 8 extra psi! Being patient and waiting for proper boost controll and fuel managemet is worth wayyyyyy more than a couple of quick ponies with the chance of harming your engine.

 

[rEclipserGST]

Have you checked the wastegate actuator arm yet? Possibly not opening/closing fully. Or maybe you should just mimic the bleeder type setup with the "T" & report back?

I feel as if you do not want to attempt the setup because you do not understand why it does what it does? Plenty of people want to turbo their cars all the time & do not understand a lick of how it actually works. But they try it anyways with little to no research. You have searched.... why not get like Nike & just do it?

 

[90gsx_luis]

i had the same problem and found out that the knob on the mbc was broken inside the mbc (it was a tine piece) try to take it apart and if you can get to the ball and spring then its good but it won't hurt to look ... hope this helps

 

[cyclist112]

I have tried different routings and settings, which is how i got to where I am, confused on if i have something wrong in my setup or a bad part. I just moved from the midwest where i had a garage and normal weather, to houston texas in a packed apt parking lot and consistent 100degree days. Therefore i have been trying to eliminate the amount of time i spend A. outside in the heat and in a parking lot working on my car, and B. limiting the amount of time that would possibly put my car in a non driveable condition, as its my daily driver for the next couple months. And I also have limited funds and tools, which also add to the reasons that i want to trial and error as little as possible. Aside from people bashing on me for random reasons, i have found the responses quite helpful in one way or another...

 

[19Eclipse90]

The way I understand it, the bleeder style boost controller is controlling the amount of pressure leakage. With the knob-portion of the controller closed, you will run wastegate pressure - straight from the wastegate to your boost source. To run more boost, the controller is opened and "bleeds" what would otherwise be boost pressure back into the intake (so as not to lose the metered air), forcing the turbocharger to compress more air (higher boost pressure) to open the wastegate . It's a controlled leak that adds to the required pressure to open the wastegate: if wastegate pressure is 10 psi and you are leaking 5 psi, the boost pressure should max out at 15 psi. Again, this is how I understand it; someone do let me know if I'm wrong.

You are assuming the knob-portion of the controller acts as a ball and spring controller and that is obviously not the case based on what you've tried.

 

[cyclist112]

"
You are assuming the knob-portion of the controller acts as a ball and spring controller and that is obviously not the case based on what you've tried. "

I must not be getting my point across if this is what you think. Let me try to explain, to the most basic point, of what I am trying to figure out...

In order to hit max boost, you could essentially cap off the wastegate nipple, because that would prevent the wastegate from opening. Is this correct?
If the above is in fact correct, then completely closing the boost controller, would be the same as capping off the nipple for the wastegate, in turn making max boost.

If both of the above are correct, then from what i draw my wastegate is stuck open(or partially open at least) since i have not gained boost from closing off the air to the wastegate.
If both of the above is in fact wrong, then again, it leads me to believe that my wastegate is stuck open or partially open, since i have ran it completely the opposite way and nothing happened... again...

Since I have never actually worked on a turbo, i state that it "leads me" to believe because i dont know if there could be something else preventing it. Also, im not sure if there is a way to test the wastegate without taking it off or not, as i really dont want to use my scissor jack to get under my car in my parking lot...

 

[dsm-man]

make sure your plugs are gapped correctly had this issue with my ladys 2g. hooked up three different boost controllers changed the plugs and presto went right back to running perfectly and allowed us to up the boost finally

 

[19Eclipse90]

"
You are assuming the knob-portion of the controller acts as a ball and spring controller and that is obviously not the case based on what you've tried. "

I must not be getting my point across if this is what you think. Let me try to explain, to the most basic point, of what I am trying to figure out...

In order to hit max boost, you could essentially cap off the wastegate nipple, because that would prevent the wastegate from opening. Is this correct?
If the above is in fact correct, then completely closing the boost controller, would be the same as capping off the nipple for the wastegate, in turn making max boost.

If both of the above are correct, then from what i draw my wastegate is stuck open(or partially open at least) since i have not gained boost from closing off the air to the wastegate.
If both of the above is in fact wrong, then again, it leads me to believe that my wastegate is stuck open or partially open, since i have ran it completely the opposite way and nothing happened... again...

Since I have never actually worked on a turbo, i state that it "leads me" to believe because i dont know if there could be something else preventing it. Also, im not sure if there is a way to test the wastegate without taking it off or not, as i really dont want to use my scissor jack to get under my car in my parking lot...

You are drawing the right conclusions. The manual lists this procedure for testing the wastegate actuator which is basically relocating the source for the boost gauge. All you will be doing is t-ing into a hose between the boost source on the j-pipe to the wastegate actuator and obtaining a peak reading. It sounds like a useless test to me because you know you are hitting within the acceptable range of the wastegate (10psi).

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Another way of going about it would be using a small hand/foot air pump with a pressure gauge to manually force the wastegate to open. You can physically see when the wastegate opens at what pressure, check the results with those above and draw a conclusion from that.

As kind of an aside and for what it's worth, I wouldn't leave the wastegate actuator disconnected from the boost source to obtain "max boost". It really isn't safe for your engine.

 

[ilikerice]

Holy monkey balls!

I had that same "MBC" on my crx. I had the same problem but assumed it was the crappy MBC. So I threw it as far as I could over the fence. I was P.O.ed!

This thread has brought a lot of light to the issue I had. I was young and dumb then, and didnt know about "bleeder" type MBC's.